Evaluate $\dfrac37r +\dfrac58s$ when $r=14$ and $s=8$.
Solution: Let's substitute $ r= {14}$ and $ s=8$ into the expression. $\phantom{=}\dfrac37 {r} +\dfrac58{s}$ $=\dfrac37( {14} )+\dfrac58({8})$ $=6+5$ $=11$